The present invention relates to a driving method for a lens (optical element) feeding device used to correct aberration of an optical pick device, and relates to the optical disk (disc) apparatus.
An optical disk recording/reproducing device is an optical information recording/reproducing device having non-contact, a large capacity, fast access and a low cost as features. Making the most of these features, the optical disk recording/reproducing device is used in various fields as a digital audio signal recording/reproducing device or an external storage device for a computer. As the application fields spread, it is being promoted to heighten the performance of the optical disk recording/reproducing device. Thus, it is indispensable to improve various performances and reliability of an optical pickup device mounted on the optical disk recording/reproducing device.
For improving the recording density in the optical disk recording/reproducing device, it is effective to shorten the wavelength of the light source and increase the numerical aperture of the object lens. As one of standards for high density optical disks (discs) using a blue-violet laser having a laser wavelength near 400 nm, there are BD (Blu-ray Disc) standards which use a high NA object lens having a numerical aperture (NA) of 0.85 and an optical disk having a recording layer protection film thickness of 0.1 mm.
As for the Blu-ray Disc, a first recording layer and a second layer are disposed in one optical disk in a thickness direction of the disk with a predetermined spacing. At the time of changeover from one recording layer to the other, therefore, spherical aberration occurs. In order to correct the spherical aberration, a movable lens is provided in front of an object lens of an optical pickup device, and spherical aberration is corrected by finely adjusting the position of the movable lens with a lend feeding device.
In this lens feeding device, the movable lens is attached to a movable frame. A stepping motor is used as a motive power source. The stepping motor is rotationally driven to move the movable frame (movable lens) in an optical axis direction.
As regards the feeding device for the optical pickup device, for example, JP-A-05-081681, JP-A-10-074369 and JP-A-2000-30381 can be mentioned. As regards the lens feeding device, for example, JP-A-07-174955 can be mentioned. As a lens driving device for optical device, for example, JP-A-2004-151300 can be mentioned.